I just upgraded to 13.04 this morning. When I signed in for the first time the original background I had used from 12.10 was there but was tiled. So I went to settings appearance and changed the way it was (stretched / tiled / fit etc.) Normally, at least in 12.10 and prior, as you changed your settings, it would actively preview it behind the appearance screen.

My issue is simple. In root user everything works fine. When I click on a default image it applies it to the background. It previews all settings before exiting. And overall is less buggy.

In my user login, the new logout / lock screen (after pressing Ctrl+Alt+Del) is clear and hard to see. It also has one part of it that is not opaque and just looks bad. I can't change the background. I tried these different methods.

Go to appearance and click on a default image that comes with the distro. no change

Went online to Google images picked one and right clicked -> set as background. No change

Ubuntu tweak -> love wallpaper HD and clicked on an image. I get a notification on my desktop that says: